Roentgen-ray tube.



No. 773,827. YPATENTED N0v'.1,19o4.

' E. THOMSON.

ROENTGEN RAY TUBE.

APPLICATION FILED rm. 14. 1898.

N0 MODEL.

UNITED STATES Patented November 1, 1904,

PATENT OEEicE.

ELIHU THOMSON, SVVAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ROENTGEN-RAY TUBE.

SPECIFICATION forming part of Letters Patent No. 773,827, dated November 1, 1904.

Application fil d February 14, 1898. Serial No. 670,221. (No model.)

To rtZZ whom, it may concern:

Be it known that I, ELIHU THoMsoN, a citi- Zen of the United States, residing at Swampscott, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Roentgen-Ray Tubes, of which the following is a specification.

My invention relates to Roentgen-ray tubes or other tubes in which a high vacuum is to be maintained; and it consists in a certain method designed to automatically maintain the vacuum at any desired point.

It is well known that the constant use of any vacuum-tube tends to gradually raise the vacuum to such a point that current cannot readily pass through the tube. It is therefore necessary from time to time to artificially lower the vacuum in order to maintain the tube in opcative condition. It has been proposed to attain this object by placing in the tube a chemical or other substance capable of giving off vapor when heated and applying heat to the said chemical when the vacuum is to be lowered. The objection to this is that the regulation is not automatic, and very delicate manipulation is required to preserve the vacuuni at the proper point. Various methods of rendering this action automatic have been proposed; but they all involve the use of some extraneous regulating devices.

My invention is based upon the fact, experimentally discovered, that the cathode-rays in a low vacuum reach a focus and are rapidly dissipated on passing such focus, while in a high vacuum they are turned, as it were, into a jet beyond the focus and can pass over considerable distances with but little scattering. I therefore locate some vacuum-regulating device or substance, preferably some vaporizable material, at such a point with relation to a cathode that in a low vacuumthat is to say, a vacuum below that at which the tube is to be maintainedthe focalized rays do not affect it to any material degree, but at such a point that when the vacuum rises the jet of rays beyond the focus will reach the material or regulating device and cause the vacuum to be slightly lowered.

In the drawings attached to this specification, which represent particular embodiments of my invention, Figure 1 is a general view of a Crookes tube arranged in accordance with my invention, while Figs. 2 and 3 are modified forms.

Referring more particularly to Fig. 1, T T are the two terminals of the tube sealed into the glass, as usual. C is a concave cathode, of any suitable material, focused on an anode A. C is an auxiliary cathode, while H is a chemical, such as hydrate of potassium, which will give 03 vapor when slightly heated, placedin a recess G. The cathode C is so adjusted that as long as the vacuum remains at about the desired point the cathode-rays therefrom reach a focus at some point intermediate and do not greatly afiect the chemical H; but if now the vacuum rises the cathode-rays from O pass in a fine stream or jet to the chemical H and cause the same to liberate vapor and to reduce the vacuum.

The form shown in Fig. 2 is slightly different in that no auxiliary cathode is used, but a small opening O is made in the anode A at such a point that when the vacuum becomes too high the cathode-rays from the cathode C will pass through the opening O and liberate vapor from the chemical H.

The tube shown in Fig. 3 is similar to the form shown in Fig. 1, but differs slightly in the relative position of the two cathodes and the chemical H.

It will be evident that various changes in form and arrangement may be made without departing from the spirit and scope of my invention.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

1. The method of regulating the degree of density of a vacuum-tube, which consists in causing rays under the influence of a decrease in density, to effect the liberation of gas from an agent within the tube.

2. The method of regulating the degree of density of a vacuum-tube, which consists in causing heat controlled by the supply-current to liberate gas from an agent within the tube at a rate greater when the density in the tube is low than when higher.

3. The method of regulating the degree of density of a vacuum-tube, which consists in causing rays generated in the tube to liberate gas from an agent within the tube at a rate greater when the density in the tube is low than when higher.

l. The method of regulating the degree of density of a vacuum-tube, which consists in causing heat generated in the tube to liberate gas from a chemical within the tube.

5. The method of regulating the degree of density of a vacuum-tube, which consists in causing heat generated by the action of the current through the tube, to liberate gas from an agent within the tube only when the density becomes low.

6. The method of regulating the degree of density of a vacuum-tube, which consists in causing the rays continuously generated in the tube during the operation thereof to act upon a gas-yielding agent with an effect varying inversely with the degree of density of the tube.

7. The method of regulating the degree of density of a vacuum-tube, which consists in causing rays continuously generated in the tube during the operation thereof to liberate gas from an agent within the tube, only when the density decreases beyond a certain point.

8. The method of regulating the degree of density of a vacuum-tube, which consists in directing the rays generated in the tube toward a gas-yielding agent within the tube from such a distance that gas will be liberated from said agent only when the density decreases beyond a certain point.

9. The method of regulating the degree of density of a vacuum-tube, which consists in causing rays continuously generated in said tube during the operation thereof, to impinge upon a gas-yielding agent within said tube with an efl'ect varying inversely with the density of the tube.

10. The method of regulating the degree of density of a vacuum-tube, which consists in causing rays having an effect varying in degree with the degree of density in the tube, to liberate gas from an agent within said tube.

11. The method of regulating the degree of density of a vacuum-tube, which consists in causing rays having an effective path which increases in length when the density decreases, to liberate gas from an agent within said path within-the tube.

12. The method of regulating the degree of density of a vacuum-tube, which consists in causing rays which extend into a jet beyond a focus, to liberate gas from an agent within the path of said jet Within said tube.

13. The method of regulating the degree of density of an X-ray tube, Which consists in causing the cathode rays to liberate gases within the tube.

14. The method of regulating the degree of density of an X-ray tube, which consists in causing the rays from a single cathode to impinge simultaneously on the anode and on a gas-yielding agent in the tube.

15. The method of regulating the degree of density of the interior of a sealed X-ray tube, which consists in liberating gas within the tube when the degree of density of the interior has become decreased by the operation of the tube. 16. The method of regulating the degree of density of a sealed X-ray tube, which consists in liberating gas within the tube by heat when the degree of density of the interior has been decreased by the operation of the tube.

17. The method of lowering the vacuum of a vacuum-tube, which consists in causing a cathode stream in the said tube to impinge upon a chemical located therein.

18. The method of automatically regulating the vacuum of a Vacuum-tube, which consists in causing the rays, at high vacua, to impinge upon a suitable substance, in such a way as to cause a lowering of the vacuum, and reducing this effect as the vacuum decreases.

in witness whereof I have hereunto set my hand this 7th day of February, 1898.

ELIHU THOMSON. WVitnesses:

DUGALD MoKILLoP, JOHN McMANUs. 

